Fighting Stress Like a Prokaryote

The bacterial proteins RelA and SpoT regulate the synthesis of the guanosine tetra- and pentaphosphate [(p)ppGpp], nucleotide effectors that regulate gene expression in response to changes in nutritional and environmental conditions. Van der Biezen et al. propose that eukaryotes may respond to stress in a similar manner. A plant homologue of RelA/SpoT, called At-RSH1, was identified in a screen for proteins that interact with a plant R protein, an agent that can respond to pathogen invasion by altering cell metabolism. The authors determined that At-RSH1 has (p)ppGpp synthetase activity and could rescue synthesis in mutant bacterial strains. Hence, like prokaryotes, plants and possibly other eukaryotes may regulate gene expression in response to stress by using the same mechanism.